Transformer grounding device



Nov. 17, 1931. A. w. THOMPSON 1,832,670

TRANSFORMER GROUNDING DEVICE Filed July 5, 1926 2 Sheets-Sheet l WITNESSES: INVENTOR MfiM/M I ATTORNEY Nov. 17, 1931. ,-w. THOMPSQN 1,832,670

TRANSFORMER GROUNDING DEVICE Filed July 3, 1926 2 Sheets-Sheet 2 INVENTOR fia/r W/Zam safi ATT'ORNEY WITNESSES:

Patented Nov.17, 1931 l UNITED PATENT orrlca mm w. 'rnomrson, or SHARON, rmmmvamn, assronoa 'ro wasrmonousn mc'rmc'a murncrumo comm, A conrorwrron or rmsxnvam rumours. (momma manor.

Application men :nu e, 1926. Serial 10.120441.

My invention relates to: electricaltransformers and switches therefor. One object of'my invention is to provide a grounding switch for transformers.

Another object of my inventioni's to pro? vide a grounding switch for transformers that shall be operable from the extension of the transformer tank.

A further object of my invention is to provide a grounding switch for electrical apparatus that shall be retained in aninoperative position when the electrical device 1s ener- In operating electrical transformers, 1t is desirable to ground .the secondary wind ng when repairs are being made. Grounding switches should be so'devised that it is impossible to ground the transformer when it 1s energized, in order-to prevent accidental grounding during the normal operatlon thereof. Accordingly, I 'have' devised agro ding switch that is operable from without lie transformer tank only when the transformer is deenergized or providing an electro magnet that cooperates with a stop member for preventing operation ofthe grounding grounding switch embodying my invention;

switch whenever the transformer is energized. Referring to the accompanying drawmgs, Fig. 1-is a front elevational view of a cam mechanism 5 together wit an electromagnet 6 that cooperates with a. stop. memher 7 constituting a portion of the cam mechanism 5.

Referring to Figs. 2 and 3, the bridging member 1 is connected, by a conducting strap particularly to 4 grounding the lower end of the frame 9 an '25 is provided, at

'8, to a metallic frame 9 that in turn, is secured by bolts 11 to a casting 12 which is secured, as at 13, by welding, to the wall of a.

transformer tank 14, so that the grounding switch is mounted internally of .the transformer tank 14. Accordingly, when the brldging member 1 engages the contact members '2 and 3, the latter are connected to ground through the strap 8, the frame 9, the casting 12 and the tank Wall 14. An extens1'on15 of insulating material is secured to contact members 2 and 3.

The contact-controlling member 4 is provided wlth a pair of slots 16 and 17 that 00- operate with a guide screw 18 and a roller 19,

respectively. The roller 19 constitutes a portion of the cam mechanism v5. a

The contact-supporting member 4 is p129- vided with rollers 21 and 22 that engage the periphery of a cam wheel 23. The cam wheel 23 is mounted on a shaft 24 that extends outwardly through the casting 12 and terminates in an operating handle 25. Suitable packing 26 is provided to insure an oil-tight joint between the shaft 24 and the casting 12.

By reason of the provision of the rollers 21 and 22, the contact-controlling member 4 1s moved upwardly and downwardly as the cam wheel 23 is turned. a

The stop member 7 is mounted at the end of the shaft 24 and cooperates with an armature member 27 of the electromagnet 6. The armature 27 is biased in a clockwise directionby a tension spring 28. The electromagnet 6 is secured to the frame-9 by bolts 29.

The armature 27 normally extends outside of the circumference of the circle described by the outer portion of the stop member-7, but, when it is attracted to its upper position by the solenoid 30 of the electromagnet 6 in 0 position to the spring 28, 'it projects into t e path of'the stop member 7 and, accordingly,

lt-is impossible to rotate the shaft 24.

9 Referring to Fig. 4, the operating handle its outer ends, with openings 31 that cooperate with an opening 32 in 'a lug 33 that is mounted on a plate 34 which is supported from the casting'12 and surrounds the shaft 24. The plate 34 is prosupports the l vided with indicia grounded and alive. When the operating shaft 24 is moved, one of the openings 31 on the handle 25 is brought into registry with the opening 32, and a padlock maybe passed through the registered openings, thereby preventing unauthorized operation of the groundmg switch.

Referring to Fig. 2, the contact members 2 and 3 are connected across the high tension winding 35 of the transformer, and the solenoid 30 of the electromagnet 6 is connected across the low voltage winding 36.

When it is desired to operate the grounding switch, the padlock securing the handle 25 to the lug 33 is removed, and pressure is applied to the handle 25. If the low-ten-' sion winding 36 is energized, the. armature 27 will be in its upper position, thereb preventing movement of the stop mem er 7, which is in its lower position when the bridging member 1 is raised. If the low-tension winding 36 is deenergized, the spring 28 contracts and the armature 27 is moved out of the path of the'lug 7; then the operator can turn the shaft 24 and thereby the cam wheel 23.

Movement of the cam wheel 23 exerts pressure on the one or the other of the rollers 21 and 22, as the case may be, and forces the contact controlling member 4 upwardly or downwardly along its slots 16 and 17. When the member 4 is moved to its lower position, shown in Fig. 1, the bridging member 1 engages the contact members 2 and 3, thereby connecting them, through the strap 8 and frame 9, to ound. When the groundin switch is in tile grounded position, the wor grounded is exposed on the plate 34.

When it is desired to put the transformer into operation, the handle 25 is turned to cover the word grounded and expose the word alive. The cam wheel 23 then bears against the roller 22 to raise the contactcontrolling me er 4 and the bridging member 1 out of engagement with the terminals 2 and 3. g

Accordin ly, I hate provided a" grounding switch %or electrical windings that may be operated from a remote point, as from the exterior of a tank. Operation of the grounding switch is prevented so long as the winding is energized, due to the presence of an electromagnet that is energized in accordance with'the connected electrical device, and the armature of which coo erates with a stop member forming a part 0 the grounding switch.

It is to be understood that such changes may be made in the arrangement, number and connection of the several parts of my invention as shall fall within the scope of the appended claims.

I claim as my invention: I

1. The combination .with windings of a transformer, of a grounding switch for one of the windings and electro-responsive means associated with another winding for preventing the operation of the grounding switch when one of the windings is energized.

2. The combination with windings of a transformer, of a grounding switch for one of the windings and means associated with another winding for preventing the operation of the grounding switch when the latter winding is energized.

3. The combination with windings of a transformer, of a grounding switch for one of the windings and an electromagnet connected to another winding for preventing the operation of the grounding switch when the latter winding is energized.

4. The combination with primary and secondary windings in inductive relation, of a grounding switch for the secondary winding and means associated with said primary winding for preventing the operation of the grounding switch when the primary winding is energized.

5. The combination with a high-tension and a low-tension winding in inductive relation, of a grounding switch for the hightension winding and an electromagnet connected to the low-tension winding for preventing the operationv of the grounding switch when the latter winding is energized.

6. The combination with an electrical de vice comprising a tank and a winding, of a grounding switch for the winding comprising a cam mounted within the tank, means for actuating the cam extending exteriorly of the tank and acontact-controlling mem- .ber actuated by the cam.

7. The combination with an electrical device comprising a tank and a winding, of a grounding switch for the,winding mounted within the tank comprising a; cam, means for actuating the cam exteriorl of the tank and a contact-controlling mem r having a reciprocable movement imparted thereto by the cam.

8. The combination with an electrical device comprising a tank and a winding, of a grounding switch for the' winding mounted within the tank comprising a cam, means for actuating the cam extending 'exteriorly 0a. the tank, a contact-controlling member having a reciprocable movement imparted'thereto bythe'cam, and an electromagnet responsive to an electrical condition of said device :for preventing the operation of the cam when the electrical device is energized.

9. The combination with an electrical device comprising a tank and windings, of a grounding switch for one winding mounted within the tank comprising a cam, means for actuating the cam extending exteriorly of the tank and a contact-controlling member having a reciprocable movement imparted thereto by the cam, and means controlled by 7 an electrical quantity in another winding for preventin the operation of the cam when the electrical device is energized.

10. The combination with windin of a. transformer, of a grounding switch $11 one of the windings and means responsive to an electrical quantity of one of the windings for preventing the operation of the ounding switch when said last named win ing is energized.

11. In combination, switch therefor comprlsing a lon itudinally movable rod, locking means for said rod nor mally held out of operative position, and electromagnetic means for moving said locking means into operative position, said last named means being controlled by current in the low tension side of the line.

In testimony whereof, I have hereunto subscribed my name this 24th day of June, 1926.

ARTHUR W. THOMPSON.

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